Metallurgical heating apparatus



March 20, 1951 H. DOBRIN METALLURGICAL HEATING APPARATUS 3 Sheets-Sheet 1 Filed Dec. 13, 1949 INVENTOR. HARRY DOBAIN.

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March 20, 1951 H. DOBRIN METALLURGICAL HEATING APPARATUS 3 Sheets-Sheet 2 Filed Dec. 15, 1949 INVENTOR. HA RR Y DOBRI/V.

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March 20, 1951 H. DOBRIN METALLURGICAL HEATING APPARATUS 3 Sheets-Sheet 5 Filed Dec. 15, 1949 INVEN TOR. HARRY Dos/qr/v.

M. W .M m L Patented Mar. 20, 1951 UNITED i-SE-TATES PATENT 110 ILCE 1 "METALIiUR'C-llCAL HEATING APPARATUS Harry. Dobrin; Tittsburglr, Pa; assignor; to Furnace- Engineers-Incorporated, Pittsburgh, :Pa., a

(corporation-1of Pennsylvania fApplic'atio'ri- December 13;19519, 'Serial' ,No. 132;700

- -4'Glaims.

1 "This invention relates:toheatingapparatus for melting: or treating-metal, and -moreparticularly -to apparatus including" means for3"exhausting =combustion-gases from" the .heating chambers.

l Included among the equipment with-whichthis he'ating apparatus maybe-used are galvanizing settings; wherein the combustion gases from the burners which heat-the galvanizing: pots may be "drawn out of 'theheatingchambers by eductors ofinstallation;provision is made forturning off I the 'eductor and--directing air backwardly through it when the burners are at their lowest *setting, sot'hatthe natural draft through" the -01, if-de1ivery-to thepot of the articlesbeing 20,

galvanized isdelayed -while the burners-are -turned-iowpthe molten zinc may--rise to too high a temperature, due to lack of--cooling= by *those articles.

It is'among-t-he objects ofthis invention to provide heating apparatus of *thee'ductor' type justreferred --to; in whichprovision i-smade for "delivering 'airto th-eeductor-tooperate it during low burningperiodsin-cas-the temperature that is being controlled' starts to rise above a predetermined maximum.

The"preferredembodimentof this-invention is "illustrated in '--the-' accompanying drawingspin ---whicI'1-EE'igi 1 is afragmentary-plan view- 'of a 1 galvanizing settingand the associated 'heating apparatus; Fig. 2 is a'fra'gmentary-side view; and Fig; 3--isan elevationof-th'e heating-apparatus of "Fig. 1.

Referringto thedrawings, the galvanizingset- 'ting' includes a melting pot 1 located in the cen-. ter of a-rectangular heating chamber 2.'-' The Wall 3 "of the chamber is provided with a series oflaterally-spaced burner openings' l into which burners 5 are directed.* --Preferab1y-, the burners -'--burn gas and are "of" the kind disclosed inmy Patent No." 2,403,431. Secondary-air enters the outer-end of the burner openings -through holes 1" in=the supporting plates BfThe burners are conn'ected-to a header 9 thatextendsaroundthe "wall "of themeating-" chamber and that is connected'by asupply-pipe 10- to the gas' supply. Below the burner-openingspilot-burners l-I-extend through wall 3.*"They'are--'c'onnected-to a smaller-header lz' thatis connected, by apipe- 13 to supply pipell].

- l pipe' l3 and them'ai'n burners; is provided uiith a 1 throttling valve' i 5 that maybe operated in: any 2 suitable :way. For eXam-ple, it maybe a diaphragrn controlled valve that is opened -"by air -....pressure"fr0m a'tube l 6 connected to the air supply pipe. I l for the maiuburnersJ-Airis: supplied *that are operated-hy-air pressure: :Inone type" 10 to this pipe by an-eleotric:b1ower l8, and-' the pipe is connectedto a header IQ extending around-the heatingchamber; 'The 'air pipecontains a throttling valve :25, by which the flow of air to the main burners is controlled. The'stem 'of-this valve isturned-by aiater'ally projecting arm 22.

It willbe seen that -as-this valve is. opened wider,

*heating chamber will-not carry out the heat too the air pressure beyondit nin pipe IT Will 1ncrease, and-the'--increased:air pressure will open gas-walv'e i 5 wider. Wherr the airsupply is reduced, the-gassupply is reduced with it.

i The products 1 of: combustion -.iwithin the fur- --nace are drawn out through a stack 26, on which an air-ope'rated eductor 21- -is -mountedJTThis eductor -includes a 'Venturi tube 28 forming a continuation 0f the staclg the tube being enber' 3! around the tube.

circled behind its narrowest part or throat by a ring-J29-We1ded thereto in order'to form asham- The uppen wallof' this chamber,-'in'si'de the tube; is provided' with a pin- :.ral-ity of circumferentiallyspaced jet hOle's SZ directed 'upwardf The ring -is *connected by a "valve 2l.- Air entering eductor"chamber 3| esbranch pipel 33 to'main! air sup'ply pipe Ii behind capes through jets 32 into the Venturi tube-and thus draws the exhaust =gases 'outthr-ough the stack from within theheating chamber. "The greater the air -fiow'cthrough"theeducton-the more rapidly the exhaust :gasesare" drawn out.

' The airflow to the 'eductor' chamber is variecl in accordance with. the rate of operation 1 of *the I burners by connecting a valve-34'inbranch pipe 33; Thestem of this valve is turriedbyan-arm 36, generallyparallel-to arni' ZZ- of the first air "valve 2 I "To keepthe heating chamber a from becoming too" cool when the burners are turned -low,-- the naturaldraft through the chamber is reduced so that there-willnotbe enough cold air-drawn in stream-of'airdown into "the eductor 2'! during low-burning periods toreduce the upwarddraft that draws air in through holes 'lI- For'this purpose an L-shapenozzle '40 is welded in the Ven- *turitubeZ 8 near itsupper end; with =-the inner end -of the nozzle directeddownward toward the throat of the tube. The outer end of the nozzle is coupled to a branch pipe 4| that is connected to the other branch air pipe 33 behind valve 34. The pipe 4| is provided with a valve 42 having a stem to which an arm 43 is connected. This arm is pivotally connected by a link 44 to the arms of the other two air valves, and it is pivotally connected by another link 45 to an arm 46 projecting from an oscillatable member 41 mounted in an electrically or pressure operated valve-actuating device 48 of known construction. If electrically operated, this device is electrically connected by wires 49 through well known electrical control apparatus (not shown) to a thermocouple 50 immersed in the spelter in pot I (Fig. 1), whereby the oscillatable member 41 is turned one way or the other, depending upon whether the galvanizing pot is calling for heat or is becoming too hot. Air valve 42 is set so that it does not open until after air valve 34 has closed and air valve 2| has been turned to its minimum setting where it nearly, but not quite entirely, shuts oif the air to the main burners. With this arrangement of valves, a back pressure is created in the eductor as soon as the air supply to its jets 32 is cut off, which occurs when the air supplied to the burners is reduced to a minimum. This back pressure prevents an undesirable amount of cool air from being drawn into the furnace through the secondary air inlets I, but it does not shut off all draft up through the eductor.

It is a feature of this invention that provision is made for preventing overheating of the spelter in pot I during periods when the burners are turned as low as possible and air is being directed downward in the eductor from nozzle 40. The overheating may happen because of accidental sticking of gas valve l or main valve 2| so that the burners are not turned as low as they should be, or because charging of the galvanizing pot with the articles that are to be galvanized may be delayed so that heat will not be absorbed by those articles as otherwise would be the case. For such emergencies a by-pass is provided around the eductor air valve 34 to al low air to be delivered to the eductor in order to draw off the combustion gases more rapidly and thus reduce the temperature in the heating chamber. nected to the main air supply pipe behind main air valve 2|, and is connected to eductor branch pipe 33 between the valve 34 therein and the eductor. As in normal operation of the apparatus this by-pass pipe is not supposed to be used, it contains a normally closed valve 55. This valve may be of any suitable type which can be opened when the temperature in the galvanizing pot rises more than a predetermined number of degrees above the maximum temperature that the spelter is supposed to have. A normally closed diaphragm valve is illustrated. This valve can be opened by air pressure delivered to it through a tube 57 connected to the main air supply pipe I? behind main valve 2i. However, this tube normally is closed by a solenoid valve 58 that also is under control of thermocouple 5D in such a manner that the valve is not energized until the temperature starts to rise above the maximum desired. It will be noted that the solenoid valve will have occasion to open only during periods of low burning when the valve 34 in the eductor pipe is closed. When the solenoid valve is opened, air pressure in tube 51 causes the diaphragm valve 56 to open and Accordingly, a by-pass pipe 55 is conallow air from the main air pipe to reach chamber 3| of the eductor and operate it. Of course, this air blows against the air being directed down into the eductor from nozzle 40, but as the pipe is larger than pipe 4|, the upward pressure and greater volume of air will overcome the downward pressure and pull the exhaust gases out of the heating chamber until the spelter has cooled to the desired temperature again. Solenoid valve 58 then will close, followed by the closing of valve 56.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. Heating apparatus for heating a chamber having an air inlet and an exhaust gas outlet, comprising a burner adapted to be directed into such a chamber, a conduit for delivering fuel to the burner, a conduit for delivering air to the burner, a first valve in said air conduit, an air operated eductor adapted to be connected to said chamber outlet, a conduit for supplying air to the eductor to operate it, a second valve in said eductor supply conduit, means for directing a stream of air backwardly in the eductor to retard the flow of exhaust gases therefrom, a conduit for delivering air to said means, a third valve in said last-mentioned conduit, means adapted to respond to the temperature in said chamber for controlling said valves to close the first and second valves as said temperature rises, means for decreasing the flow of fuel to the burner as the fiow of air thereto is decreased, said valves being so arranged that said third valve opens as said first and second valves are moved toward closed position, an air conduit by-passing said second valve, a normally closed valve in said by-pass conduit, and means adapted to respond to a predetermined maximum temperature in said chamber for opening said normally closed valve, whereby to deliver air through said by-pass conduit to the eductor to operate it while said second valve is closed and said third valve is open.

2. Heating apparatus for heating a chamber having an air inlet and an exhaust gas outlet, comprising a burner adapted to be directed into such a chamber, a conduit for delivering fuel to the burner, a conduit for delivering air to the burner, a first valve in said air conduit, an air operated eductor adapted to be connected to said chamber outlet, a conduit for supplying air to the eductor to operate it, a second valve in said eductor supply conduit, means for directing a stream of air backwardly in the eductor to retard the flow of exhaust gases therefrom, a conduit for delivering air to said means, a third valve in said last-mentioned conduit, means adapted to respond to the temperature in said chamber for controlling said valves to close the first and second valves as said temperature rises, means for decreasing the flow of fuel to the burner as the flow of air thereto is decreased, links operatively connecting said valves for opening said third valve as said first and second valves move toward closed position and for opening the burner, a conduit for delivering air to the burner, a first valve in said air conduit, an air operated eductor adapted to be connected to said chamber outlet, a conduit for supplying air to the eductor to operate it, a second valve in I said eductor supply conduit, means for directing a stream of air backwardly in the eductor to retard the flow of exhaust gases therefrom, a "conduit for delivering air to said means, a third valve in said last-mentioned conduit, means adapted to respond to the temperature in said chamber for controlling said valves to close the first and second valves as said temperature rises, means for decreasing the flow of fuel to the burner as the flow of air thereto is decreased, said valves being so arranged that said third valve opens as said first and second valves are moved toward closed position, an air conduit by-passing said second valve, a normally closed'air preshaving an air inlet and an exhaust gas outlet, comprising a burner adapted to be directed into such a chamber, a conduit for delivering i'uel to the burner, a conduit for delivering air to the burner, a first valve in said air conduit, an air operated eductor adapted to be connected to said chamber outlet, a conduit for supplying air to the eductor to operate it, a second valve in said eductor supply conduit, means for directing a stream of air backwardly in the eductor to retard the flow of exhaust gases therefrom, a conduit for delivering air to said means, a third valve in said last-mentioned conduit, valveactuating means having an electrically operated valve-actuating member, means adapted to respond to the temperature in said chamber for controlling the movements of said member, links pivotally connected to said member, control arms for said valves pivotally connected to said links,

whereby said actuating means closes the first and second valves as said temperature rises and simultaneously opens the third valve, means for decreasing the flow of fuel to the burner as the flow of air thereto is decreased, an air conduit by-passing said second valve, a normally closed valve in said by-pass conduit, and means adapted to respond to a predetermined maximum temsure actuated valve in said by-pass conduit, a

perature in said chamber for opening said normally closed valve, whereby to deliver air through said by-pass conduit to the eductor to operate it while said second valve is closed and said third valve is open.

HARRY DOBRIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,360,167 Schumann Oct. 10, 1944 2,446,642 Dobrin Aug. 10, 1948 2,479,940 Kuhner Aug. 2-3, 1949 

